Wastes, under normal conditions, are gradually broken down or biodegraded by indigenous microorganisms in the environment. However, biodegradation reactions are often hindered by environmental fluctuations such as changes in temperature, pH, salinity, water and air supply, etc. For example, wastes such as fat and grease are biodegraded by microorganisms to fatty acids and glycerol. In the presence of oxygen the fatty acids are further metabolized with the end product being carbon dioxide and inert by-products. Glycerol is also metabolized as an efficient energy source.
Waste water systems, for example those in the food service industry, typically incorporate a grease trap to capture grease and other contaminants from the passing flow of wastewater and to store such contaminants for eventual removal from the trap. Typically, the grease trap is accessed periodically and the contaminants removed for eventual disposal. Grease and other contaminants often build up very quickly in such traps. If they are not removed in a timely fashion, the ability of the trap to operate efficiently, or at all, is seriously affected. When a trap is no longer functional, the contaminants will bypass the trap and flow into areas that are intended to be free from these contaminants. Specifically, the contaminants will either clog up the waste water system or will flow into the municipal sewer system in violation of local ordinances or state laws. Most grease traps require relatively large compartments, particularly if the associated food service facility operates on a large volume.
A variety of approaches have been developed to increase the required period between subsequent cleanings of a grease trap by increasing the bio-degradation by microorganisms of grease in the trap. One approach to enhancing bio-degradation of grease in a grease trap is to introduce chemicals or nutrients to the trap to aid naturally occurring bacteria or microorganisms in the trap. For example, U.S. Pat. No. 5,340,376 granted to Cunningham discloses a controlled-release nutrient source that adds nutrients at low levels to a biodegradation environment to enhance microorganisms' growth and activity and promote the effectiveness of the biodegradation in removing environmental contaminants. The nutrients are in the form of coated solid particles, each having a core of water-soluble microorganisms nutrients encapsulated in a release rate-controlling coating. The effectiveness of biodegradation of wastes by enhancing the growth of naturally occurring bacteria or microorganisms with the introduction of a controlled-release nutrient source is still hindered due to environmental fluctuations such as changes in temperature, pH, salinity, water and air supply, etc.
Another approach to enhancing bio-degradation of grease in a grease trap is to introduce a structure upon which indigenous microorganisms can bind and grow, and thus effectively remain in the grease trap. For example, U.S. Pat. No. 4,925,564 and U.S. Pat. No. 4,670,149 both granted to Francis disclose a bacterial incubator device having an enclosure with a foraminous wall structure packed with high surface area elements such as spherical packing of a shape or size to multiply the solid bacterial growth surface area in a grease trap. The incubator is positioned at the interface of floating grease and water. Similarly, the effectiveness of biodegradation of wastes by enhancing the growth of naturally occurring bacteria or microorganisms with the introduction of a support structure is often hindered due to environmental fluctuations such as changes in temperature, pH, salinity, water and air supply, etc.
Still another approach to enhancing bio-degradation of grease in a grease trap is to introduce additional microorganisms into the grease trap. For example, U.S. Pat. No. 5,271,829 granted to Heppenstall discloses a treatment system for wastewater that includes a dispenser for introducing treatment material, a solution of bacteria, into a grease trap for the purpose of digesting the grease that is separated from wastewater as it flows through the grease trap. The dispenser includes a housing having a compartment for holding a quantity of grease digesting material and a dispensing opening at the lower end of the compartment. A restrictor is located at the dispensing opening permitting the digesting material to pass at a constant restrictive rate from the dispensing opening to the grease to be treated in a chamber of the grease trap. The grease digesting material in the dispenser will naturally go through a four-phase growth cycle (i.e., lag, exponential, stationary, and death, further described in detail in a Bacterial Growth Section below) that limits its effectiveness of enhancing the bio-degradation of grease on an extended or continuous basis.
Another example of introducing additional microorganisms in to a grease trap is U.S. Pat. No. 5,225,083 granted to Pappas, et al. Pappas, et al. discloses a simple method that includes adding endemic bacterial microorganisms to one or more of the drain lines for ultimate introduction into the grease trap and biodegrading grease. Depending on the bacterial microorganisms' growth cycle phases, the effectiveness of the bio-degradation of grease by the microorganisms will vary.
Another approach to enhancing bio-degradation of grease in a grease trap is to introduce enzymes into the grease trap to solubilize the grease. For example U.S. Pat. No. 4,940,539 granted to Weber discloses a grease trap comprising a housing having an inlet to receive wastewater containing grease and an outlet. The wastewater within the housing is heated by an electric heating element that is immersed in the wastewater and the heating element is controlled by a thermostat to maintain a desired temperature of the water within a given range. An aqueous composition containing a mixture of enzymes and bacterial spores is introduced into the housing into contact with the wastewater. The enzymes solubilize the grease while the bacteria spores biodegrade the grease. However, the ability of the bacteria to biodegrade waste will be delayed in that the bacterial spores first enter a lag phase requiring a period of time before entering an exponential growth phase in which to begin bio-degradation of the waste.
Another example, U.S. Pat. No. 4,882,059 granted to Wong, et al. discloses a method for solubilizing particulate materials in waste water which comprises the steps of cultivating aerobic bacteria in the presence of oxygen in an activator solution containing a food source until the level of the food source drops below a predetermined level causing the bacteria to begin producing increased amounts of enzymes and thereafter contacting the activated bacteria and enzymes with the particulate materials under conditions which solubilize the waste. Another example, shown in U.S. Pat. No. 5,171,687 granted to Moller, et al., discloses an apparatus for culturing and delivering microbes for waste treatment in a flow system. The apparatus includes a container having a first and second chambers. The first chamber is maintained in a nutrient rich environment for the source microbial matter supported therein while the second chamber is nutrient deficient. Water is introduced into the first chamber at a predetermined rate and flows through an outlet into the second chamber. The outlet of the second chamber is directed to a flow system benefiting from the activity of the microbial matter. In both Wong and Moller, et al., it is believed that starving the bacteria of nutrients activates enzyme production therein to aid in solubilizing particulate materials in waste water. Although the enzymes aid in solubilizing the grease, the bacteria will be ineffective in biodegrading the solubilized grease in that the bacteria being nutrient deficient will enter a stationary phase (if not death phase) necessitating that the bacteria enters a lag phase, requiring a period of time before the bacteria enters an exponential growth phase in which to begin to biodegrade the grease. In addition, enzyme hydrolysis by itself is believed to merely cause intact fatty acids to be produced which are likely to redeposit further down the sewer lines causing even greater commercial environmental damage.
Another example, U.S. Pat. No. 5,840,182 granted to Lucido et al. discloses an apparatus for incubating microorganisms and delivering microorganisms to an environment containing waste for bio-augmenting the bio-degradation of waste. This apparatus comprises three separate containers each containing a specific content. The three containers are arranged in a specific orientation and this arrangement mandates a directed flow of fluid. The first container has a bioreactor vessel containing a bacterial culture. The second container has a chamber containing an aqueous solution of inorganic nutrients and a third container has a chamber containing an aqueous solution of organic nutrients. The third container being operably linked in a one-way fluid communication between the first container and the second container. The apparatus also contains a controller having a means for introducing a supply of the inorganic solution from the second container to the organic solution of the third container and a means for removing a portion of the bacterial culture from the first container and delivering it to the environment to be treated.
As stated above, the specific three container arrangement requires that the flow of aqueous inorganic solution in the second container be supplied to the organic nutrient containing third container. Once the inorganic solution of the second container mixes with the organic nutrients in the third container, a portion of the solution is supplied to the first container. The amount of inorganic nutrients provided to the third container from the second container is controlled by a pump in the controller. However, the amount of organic nutrients that dissolves in the aqueous inorganic solution supplied to the third container from the second container and then supplied to the first container, is not metered. Since the amount of organic nutrients that dissolves in the inorganic solution is affected by physical properties such as temperature pressure concentration etc., the amount of organic nutrients provided to the bioreactor will fluctuate as these physical properties fluctuate. This makes stabilizing fluid conditions in the bioreactor, so as to maintain the microorganisms in exponential growth, almost impossible. As a result, the microorganisms dosed to the environment to be treated by the controller are not always in the exponential phase of growth. Thus, the ability of the microorganism to biodegrade waste will diminish, causing system failures that may result in clogging and increased maintenance of the apparatus.
If the environment of the bioreactor changes and causes the microorganisms to exit the exponential phase of growth, in order to return the microorganisms back to the exponential growth phase (so as to be most productive in bio-degrading waste) restabilization of the bioreactor environment is required. In other words, stabilization of the aqueous environment in the bioreactor, including the amount of organic and inorganic nutrients, is required.
Assuming conditions can be stabilized, the microorganisms will still have to pass through a lag phase in order to return back to the exponential growth phase. If the amount of fluid, nutrients and/or the physical properties such as temperature, pH, salinity, etc., fluctuate during this period it will disrupt the re-stabilization process of the bioreactor and even further delay the return of the microorganisms to exponential growth. Any microorganisms dosed to the waste environment during this period will not be in the exponential growth phase and therefore will not actively bio-degrade waste.
Moreover, assuming that the microorganisms in the bioreactor return to the exponential growth phase, once the concentration of inorganic and organic nutrients fluctuate in the bioreactor, the microorganisms will again exit the exponential growth phase and the cycle will begin all over again. As a result, the waste in the environment being treated will not be bio-degraded and backups and clogs are likely to occur. As a result, waste may spill over into areas not intended for waste, and/or even cause waste to spill into the public sewage system in violation of local, state and/or federal laws.
There is a need for a waste bio-augmentation system for treatment of contaminants and waste products that is able to maintain the environment of the bioreactor, including the amount of fluid, organic nutrients, inorganic nutrients and other physical properties, so as to keep the microorganisms of the bioreactor in an exponential phase of growth. The microorganisms can then be delivered on a continuous or periodic basis to an environment containing contaminants and/or waste products for effectively bio-augmenting the bio-degradation of these contaminants and/or waste products. Such a system would require less maintenance and therefore be less expensive to operate. The present invention overcomes the shortcomings of existing systems.